• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.350-354
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• 2018

Lifetime study of blue phosphorescent and thermally activated delayed fluorescent organic light-emitting diodes was carried out to understand the dominant degradation process during electrical operation of the devices. Doping concentration dependence of the phosphorescent and thermally activated delayed fluorescent organic light-emitting diodes was studied, which demonstrated long lifetime at low doping concentration in the phosphorescent devices and at high doping concentration in the thermally activated delayed fluorescent devices. Detailed mechanism study of the two devices described that triplet-triplet annihilation is the main degradation process of phosphorescent organic light-emitting diodes, whereas triplet-polaron annihilation is the key degradation factor of the thermally activated delayed fluorescent devices.

• Tribology and Lubricants
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• 제11권5호
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• pp.1-9
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• 1995

The mechanism of various spherical particles formation from wide range of tribo-systerns is suggested and deduced by the action of micro-explosion on the basis of the thermally-activated wear theory, in which the flash temperature at contact could be reached clearly upto the material molten temperature due to the secondary activation energy from the exothermic reactions involving lubricant thermo-decomposition, metals oxidation, hydrogen reactions and other possible complex thermo-reactions at the contacts. Various shapes of spherical particles generated from the tribosystem can be explained by the toroidal action of micro-explosion accompanied with the complex thermo-chemical reactions at the contact surfaces or sub-surfaces.

• 한국전기전자재료학회논문지
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• 제36권3호
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• pp.241-248
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• 2023

연구를 통해 산출하는 실험 데이터의 가치는 그 데이터를 합리적 가설을 바탕으로 정확하게 분석했을 때 빛난다. 재료 분야의 연구자들이 접하는 실험 데이터의 상당수가 열적 활성화 과정을 통해 발현되는 물리 화학적 특성 값이다. 하지만 열적 활성화 과정에 대한 오해로 인해 잘못된 분석 결과를 도출하고 이를 통해 잘못된 결론을 보고하는 경우가 많다. 본 논문에서는 열적 활성화 과정의 의미를 다시 한번 살펴본 뒤, 실제 잘못 해석된 채로 출간되었던 데이터를 예시로 분석 결과의 유효성을 판단하는 기준에 대한 논의 및 재분석하는 과정을 단계적으로 보여줌으로써 향후 유사한 데이터를 획득했을 시 정확한 분석을 진행할 수 있는 역량을 기르는 데 목적을 두고 있다.

• 신재생에너지
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• 제10권1호
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• pp.20-29
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• 2014

The present study investigated the effects of thermal pre-treatment on the enhancement of anaerobic biodegradability of waste activated sludge at varied TS concentration levels. The activated sludges were thermally oxidized for 30 minutes at $80{\sim}200^{\circ}C$ with varied TS concentrations (2%, 4% and 6%). and then, sludge characteristics, solubilization efficiency and methane production yield of thermally pre-treated sludges were analyzed. The higher the temperature in the thermal pre-treatment, the higher the concentration levels of dissolved matters such as $SCOD_{Cr}$, $NH_4{^+}$ and VFAs, which indicates that the thermal pre-treatment facilitates the hydrolysis and acid fermentation. Furthermore, the solubilization efficiency was increased in proportion to the temperature rise at all TS concentrations and was reached at 68.9%, 55.6% and 53.1%, respectively, at $200^{\circ}C$. In the BMP test of the pre-treated sludges, higher methane production yields were observed as 0.313. 0.314 and $0.299m^3\;CH_4/kg\;VS_{add}$ at the condition of TS 2% ($160^{\circ}C$), 4% ($160^{\circ}C$) and 6% ($180^{\circ}C$), respectively, and degradation rate was increased by 84%, 79% and 65% compared with non-pretreated waste activated sludge. These findings suggest the effectiveness of thermal pre-treatment of waste activated sludge for anaerobic biodegradable process.

• Membrane and Water Treatment
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• 제14권1호
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• pp.1-10
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• 2023

This study explored the feasibility of calcium-rich food waste, Mactra veneriformis shells (MVS), as an adsorbent for phosphate removal, and its removal efficiency was enhanced by the thermal activation process. The CaCO3 in MVS was converted to CaO by thermal activation (>800 ℃), which is more favorable for adsorbing phosphate. Thermal activation did not noticeably influence the specific surface area of MVS. The MVS thermally activated at 800 ℃ (MVS-800), showed the highest phosphate adsorption capacity, was used for further adsorption experiments, including kinetics, equilibrium isotherms, and thermodynamic adsorption. The effects of environmental factors, including pH, competing anions, and adsorbent dosage, were also studied. Phosphate adsorption by MVS-800 reached equilibrium within 48h, and the kinetic adsorption data were well explained by the pseudo-first-order model. The Langmuir model was a better fit for phosphate adsorption by MVS-800 than the Freundlich model, and the maximum adsorption capacity of MVS-800 obtained via the Langmuir model was 188.86 mg/g. Phosphate adsorption is an endothermic and involuntary process. As the pH increased, the phosphate adsorption decreased, and a sharp decrease was observed between pH 7 and 9. The presence of anions had a negative impact on phosphate removal, and their impact followed the decreasing order CO₃^2- > SO₄²- > NO₃^- > Cl^-. The increase in adsorbent dosage increased phosphate removal percentage, and 6.67 g/L of MVS-800 dose achieved 99.9% of phosphate removal. It can be concluded that the thermally treated MVS-800 can be used as an effective adsorbent for removing phosphate.

• 마이크로전자및패키징학회지
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• 제20권4호
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• pp.65-68
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• 2013

A novel bumping process using solder bump maker (SBM) is developed for fine-pitch flip chip bonding. It features maskless screen printing process. A selective solder bumping mechanism without the mask is based on the material design of SBM. Maskless screen printing process can implement easily a fine-pitch, low-cost, and lead-free solder-on-pad (SoP) technology. Its another advantage is ternary or quaternary lead-free SoP can be formed easily. The process includes two main steps: one is the thermally activated aggregation of solder powder on the metal pads on a substrate and the other is the reflow of the deposited powder on the pads. Only a small quantity of solder powder adjacent to the pads can join the first step, so a quite uniform SoP array on the substrate can be easily obtained regardless of the pad configurations. Through this process, an SoP array on an organic substrate with a pitch of 130 ${\mu}m$ is, successfully, formed.

• E2M - 전기 전자와 첨단 소재
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• 제9권9호
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• pp.918-924
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• 1996

A downstream oxygen plasma is generated by capacitively coupled RF power and applied to photoresist stripping. Stripping rate (ashing rate) is measured in terms of RF power, chamber pressure, oxygen flow rate and temperature. Ashing reaction is thermally activated and depends on oxygen radical density. The ashing process is optimized to have the high ashing rate, good uniformity and minimal plasma damage using a statistical method.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.457-465
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• 2014

Size-controlled lead sulfide (PbS) quantum dots were synthesized by the typical hot injection method using oleic acid (OA) as the stabilizing agent. Subsequently, the ligand exchange reaction between OA and thioacetic acid (TAA) was employed to obtain TAA-capped PbS quantum dots (PbS-TAA QDs). The condensation reaction of the TAA ligands on the surfaces of the QDs enhanced the conductivity of the PbS-TAA QDs thin films by about 2-4 orders of magnitude, as compared with that of the PbS-OA QDs thin films. The electron transport mechanism of the PbS-TAA QDs thin films was investigated by current-voltage (I-V) measurements at different temperatures in the range of 293 K-473 K. We found that the charge transport was due to sequential tunneling of charge carriers via the QDs, resulting in the thermally activated hopping process of Arrhenius behavior.

• 대한금속재료학회지
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• 제49권11호
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• pp.823-830
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• 2011

Structural change in an amorphous alloy was measured by applying a load below the global yield stregth at ambient temperatures. It was observed that the magnitude of the apparent structural change occuring in the amorphous alloy is determined by the compatative relationship between the stress-induced disordering process and the thermally-activated relaxation process. Structural disorder was observed to take place even at a stress well below the global yield, and the degree of the disorder was increased abruptly at the earlier stage of loading and saturated with time. In the mean time, unlike the previous belief, the relaxation process was observed to occur even at embient temperatures, and the degree of the relaxation was observed to increase linearly with time. The analytical equation predicting the structural change was proposed.

• 한국세라믹학회지
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• 제43권2호
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• pp.131-135
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• 2006

In this study, the dielectric, magnetic and transport properties of $Gd_{0.33}Sr_{0.67}FeO_3$ have been analyzed. The dielectric loss anomaly was found to be around 170 K. The activation energy corresponding to relaxation process of this dielectric anomaly was 0.17 eV. From the temperature dependence of the characteristic frequency, we concluded that the elementary process of the dielectric relaxation peak observed is correlated with polaron hopping between $Fe^{3+}\;and\;Fe^{4+}$ ions. The electrical resistivity displayed thermally activated temperature dependence above 200 K with an activation energy of 0.16 eV. In addition, the temperature dependence of thermoelectric power and resistivity suggests that the charge carrier responsible for conduction is strongly localized.